Robot and arm assembly thereof

ABSTRACT

An arm assembly of a robot includes a servo coupled to the chest of the robot, an upper arm driven by the servo, a forearm rotatably coupled to the upper arm, a hand connected to an end of the forearm and rotatable about a first axis extending along a lengthwise direction of the forearm; and a hand transmission mechanism configured to transmit motion from the servo to the hand so as to drive the hand to rotate about the first axis.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No.201811512720.0, filed Dec. 11, 2018, which is hereby incorporated byreference herein as if set forth in its entirety.

BACKGROUND 1. Technical Field

The present disclosure generally relates to robots, and particularly toa robot and its arm.

2. Description of Related Art

A servo is a key component of some robots. Generally, one servo canprovide one rotational degree of freedom. In order to imitate humanactions, a humanoid robot usually needs many servos to provide the sameamount of rotational degrees of freedom. It is useful and desirable toprovide a robot that needs fewer servos.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood withreference to the following drawings. The components in the drawings arenot necessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the present embodiments.Moreover, in the drawings, all the views are schematic, and likereference numerals designate corresponding parts throughout the severalviews.

FIG. 1 is an isometric view of a robot according to one embodiment.

FIG. 2 is an isometric partially exploded view of an arm assembly of therobot of FIG. 1.

FIG. 3 is an isometric view of the leg assembly of the robot of FIG. 1,with certain components omitted for clarity.

FIG. 4 is similar to FIG. 3 but viewed from a different perspective.

FIG. 5 is an isometric partially exploded view of the arm assembly ofFIG. 4.

FIG. 6 is an isometric view of the leg assembly of the robot of FIG. 1,with certain components omitted for clarity.

FIG. 7 is similar to FIG. 5 but viewed from a different perspective.

FIG. 8 is an isometric partially exploded view of an arm assembly of therobot of FIG. 1.

FIG. 9 is an isometric exploded view of an arm assembly of the robot ofFIG. 1.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings, in which likereference numerals indicate similar elements. It should be noted thatreferences to “an” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references can mean “atleast one” embodiment.

The terms “upper”, “lower”, “left” and “right”, indicating theorientational or positional relationship based on the orientational orpositional relationship shown in the drawings, are merely forconvenience of description, but are not intended to indicate or implythat the device or elements must have a particular orientation or beconstructed and operated in a particular orientation, and thereforeshould not be construed as limiting the present invention. The terms“first” and “second” are used for descriptive purposes only and are notto be construed as indicating or implying relative importance orimplicitly indicating the number of technical features. The meaning of“multiple” is two or more, unless expressly stated otherwise.

Referring to FIGS. 1-4, in one embodiment, a robot includes an armassembly 1000 and a chest 200. The arm assembly 1000 includes a servo 10coupled to the chest 200, an upper arm 20 driven by the servo 10, aforearm 30 rotatably coupled to the upper arm 20, and a hand 40connected to an end of the forearm 30 and rotatable about a first axis401 extending along a lengthwise direction of the forearm 30, and a handtransmission mechanism 50 to transmit motion from the servo 10 to thehand 40 so as to drive the hand 40 to rotate about the first axis 401.

With such configuration, the arm assembly uses only one servo to drivethe upper arm 20 and the hand 40, which saves cost and facilitatessimplification of motion control algorithm of the robot.

The servo 10 is fixed in the chest 200 and is electrically connected toa main control processor and executes motion commands from the maincontrol processor. The output shaft 101 of the servo 10 is coupled tothe arm assembly 1000 for driving the arm assembly 1000.

In one embodiment, the upper arm 20 includes two shells 21 connected toeach other. The forearm 30 includes two shells 31 connected to eachother. The hand 40 includes two shells 44 connected to each other. Theupper arm 20 and the forearm 30 are pivotally connected to each other bya pivot shaft 63. Both the upper arm 20 and the forearm 30 include amounting portion for mounting the pivot shaft 63. An upper-arm shield 22is provided at the upper end of the upper arm 20. The forearm 30includes a forearm shield 32.

In one embodiment, the arm assembly 1000 further includes a rotary joint70 fixed to the output shaft 101 of the servo 10 and the upper arm 20.The rotary joint 70 transmits motion from the output shaft 101 of theservo 10 to the upper arm 20 such that the upper arm 20 can rotate withrespect to the chest 200 about an axis of rotation 701. Referring toFIG. 9, the output shaft 101 of the servo 10 and the rotary joint 70 arecoaxially and fixedly connected to each other via a connecting member 70a. The output shaft 101 of the servo 40 and the rotary joint 70 a areconnected to each other by profile shaft connection that is a connectiontechnique that uses a shaft and a shaft hole both having non-circularcross section. The rotary joint 70 a and the rotary joint 70 areconnected to each other by profile shaft connection. In the embodiment,the connecting member 70 a includes a shaft 71 has a non-circular crosssection and the rotary joint 70 defines a shaft hole that is shaped andsized according to the shaft. The shaft of the connecting member 70 a isinserted in to the shaft hole of the rotary joint 70, which allows therotary joint 70 to rotate together with the connecting member 70 a. Inthe embodiment as illustrated in FIG. 8, the two shells 21 each define ashaft hole 214 and opposite ends of the shaft 71 of the connectingmember 71 a are fit in the shaft holes 214.

Referring to FIGS. 4-5 and 8-9, in one embodiment, the arm assembly 1000further includes a rotating member 80 rotatably connected to the rotaryjoint 70. The rotating member 80 and the rotary joint 70 are coaxial.The rotating member 80 is rotatable about the rotation axis of therotary joint 70. The rotary joint 70 defines a receiving hole 72. Therotating member 80 includes a shaft 81 that is fit in the receiving holeto rotatably connect the rotating member 80 to the rotary joint 70. Therotating member 80 includes a first lever 82 and a second lever 83 thatare circumferentially spaced apart from each other. The arm assembly1000 further includes a fixed post 90 securely connected to the chest200. The second lever 83 is used to contact the fixed post 90 such thatthe rotating member 80 can be pushed by the fixed post 90 to rotate withrespect to the rotary joint 70. When the rotating member 80 rotates to aposition where the first lever 82 comes into contact with the handtransmission mechanism 50, the hand transmission mechanism 50 starts tooperate to drive the hand to rotate about the first axis 401 extendingalong a lengthwise direction of the forearm 30. The fixed post 90 andthe second lever 83 are in a same vertical plane. When the servo 10drives the rotary joint 70 to rotate, the fixed post 90 can come intocontact with and apply a push force to the second lever 83, therebyrotating the rotating member 80. The arm assembly 1000 has a forearmtransmission member 60 including a first end rotatable with respect tothe chest 200 and a second end coupled to the forearm 30. The upper arm20, the forearm 30 and the forearm transmission member 60 are arrangedin such a way that the forearm 30 rotates when the upper arm 20 rotateswith respect to the chest 200. The first end of the forearm transmissionmechanism 60 is rotatably coupled to the fixed post 90. The rotary joint70 defines a groove 73 passing therethrough. One end of the fixed post90 passes through the groove 73 and one of the two shells 21. The groove73 is arc-shaped and centered on the rotation axis of the rotary joint70. The fixed post 90 is located below the output shaft 101 of the servo10.

Referring to FIGS. 2-4 and 8-9, in one embodiment, the hand transmissionmechanism 50 includes a first sliding member 51 slidably connected tothe upper arm 20 and urged to move by the first lever 82, a secondsliding member 52 slidably connected to the forearm 30 and urged to moveby the first sliding member 51, and a worm 53 rotatably mounted to theforearm 30 and connected to the hand 40. The worm 53 has a helical tooth531 that abuts against the second sliding member 52 so as to rotate whenpushed by the second sliding member 52. Referring to FIGS. 6 and 7, theservo 10 drives the rotary joint 70 to rotate. The position of the fixedpost 90 is fixed. When the rotary joint 70 rotates in a clockwisedirection, the rotating member 80 rotates together with the rotary joint70 and the second lever 83 approaches the fixed post 90. After thesecond lever 83 comes into contact with the fixed post 90, furtherrotation of the rotary joint 70 will cause the rotating member 80 torotate, in a counterclockwise direction, with respect to the rotaryjoint 70. The first lever 82 then pushes the first sliding member 51 tomove downward. The first sliding member 51 then pushes the secondsliding member 52 to move downward. Since the lower end of the secondsliding member 52 abuts against the helical tooth 531, the worm 53rotates as the second sliding member 52 moves downward, which drives thehand 40 to rotate about the first axis 401 extending along a lengthwisedirection of the forearm 30.

Referring to FIGS. 2, 8 and 9, the upper arm 20 has a longitudinal rib211 extending along the longitudinal direction thereof and two lateralribs 212 spaced apart from each other. The first sliding member 51includes an L-shaped limiting wall 511, and the first sliding member 51and the limiting wall 511 form a recess 512. The longitudinal rib 211and the recess 512 corporately define a sliding direction of the firstsliding member, and the limiting wall 511 and the lateral ribs 212corporately define a moving range of the first sliding member. Referringto FIG. 3, the forearm 30 defines a sliding groove 311 extending alongthe lengthwise direction thereof for slidably receiving the secondsliding member 52 therein. The forearm 30 defines a through hole 316through which the worm 53 passes. The outer surface of the worm 53 isprovided with a limiting portion 532. The limiting portion 532 isengaged with the inner wall of the forearm 30 to prevent axial movementof the worm 53 so that the worm 53 can only rotate.

Referring to FIGS. 3, 8 and 9, one of the two shells 31 is provided witha through hole 312. The upper abutting end of the second sliding member52 passes through the through hole 312 to abut against the lowerabutting portion of the first sliding member 51. Both the upper abuttingend of the second sliding member 52 and the lower abutting portion ofthe first sliding member 51 are provided with abutting slopes, so thatthe first sliding member can easily push second sliding member 52 tomove. The lower abutting portion of the second sliding member 52 has anabutting curved surface adapted to the helical tooth 531, so that thelower abutting portion of the second sliding member 52 can easily pushthe helical tooth 531 to rotate the worm 53.

Referring to FIGS. 2, 3 and 9. in one embodiment, the hand transmissionmechanism 50 further includes a first elastic member 54 connected to theupper arm 20 and used to return the first sliding member 51 to itsoriginal position when the first lever 82 is disengaged from the firstsliding member 51, and a second elastic member 55 connected to theforearm 30 and used to return the worm 53 to its original position. Thefirst elastic member 54 may be a spring. The first sliding member 51includes a post 513 on which the first elastic member 54 is mounted. Theupper arm 20 includes a wall 213 against which an end of the firstelastic member 54 abuts. When the rotating member 80 pushes the firstsliding member 51, the first elastic member 54 is compressed. When thefirst arm 82 of the rotating member 80 is disengaged from the firstsliding member 51, the restoring force of the first elastic member 54returns the first sliding member 51 to its original position. The secondelastic member 55 can be a torsion spring arranged around the worm 53.Two arms of the torsion spring are respectively connected to the forearm30 and the worm 53.

Referring to FIGS. 5-7 and 9, in one embodiment, the forearm 30 definesa recess 313. The forearm transmission mechanism 60 is a linkage bar 61and the linkage bar 61 includes a sliding post 611 at the second endthat is movably received in the recess 313. The sliding post 611 and therecess 313 are configured in such a way that the forearm transmissionmechanism 6 pulls the forearm to rotate with respect to the upper armwhen the upper arm starts to rotate upward from an original position.Specifically, the upper arm 20, the lower arm 30, the forearmtransmission mechanism 60 and the chest 200 corporately form a four-barlinkage mechanism. When the servo 10 drives the upper arm 20 to rotate,the forearm transmission mechanism 60 pulls, via the sliding post, theforearm 30 to flex. That is, the forearm 30 is pulled to rotate towardthe upper arm 20.

In one embodiment, the forearm 30 defines a sliding groove 314 that isin communication with the recess 313. The sliding post 611, the recess313 and the sliding groove 314 are configured in such way that thesliding post 611 moves out of the recess 313 and into the sliding groove314 after the forearm 30 has rotated for a predetermined angle. Thesliding groove 314 is arch-shaped and centered on the rotation axis ofthe forearm 30. The recess 313 extend in the radial direction andarranged at the end of the sliding groove 314 away from the fixed post90. In one embodiment, the arm assembly 1000 further includes a fourthelastic member 62 to apply a restoring force to the forearm 30 so as todrive the forearm 30 to rotate such that the arm assembly 1000 returnsback to a fully extended slate, after the upper arm has rotated for apreset angle. The fourth elastic member 62 can be a torsion spring, andthe torsion spring is arranged around the pivot shaft 63 that connectsthe upper arm 20 to the forearm 30. Two arms of the torsion spring abutagainst the upper arm 20 and the forearm 30, respectively. After theupper arm 20 has rotated back to its original position, the sliding post611 will move from the sliding groove 314 back to the recess 313.

Referring to FIGS. 1-2 and 8-9, in one embodiment, the forearm 30includes a protrusion 315 that is configured in such a way that theprotrusion 315 applies a push force to the hand 40 when the hand rotatesabout the first axis 401 and comes into contact with the protrusion 315such that the hand 40 rotates with respect to the forearm 30 about asecond axis 402 that is perpendicular to the first axis 401. That is,the dorsum of the hand 40 rotates toward the forearm 30. The hand 40 isrotated by the worm 53. During the rotation, the protrusion 315 willcome into contact with the hand 40. Since the protrusion 315 has atransitional arc surface, the hand 40 will be pushed to rotate.

Referring to FIG. 9, the hand 40 includes a third elastic member 56 toapply a restoring force to the hand 40 to rotate the hand 40 about thesecond axis 402 from an extension state to an original state.Specifically, the hand 40 is rotatably connected to one end of the worm53 via a pivot shaft 57. The rotation axis between the hand 40 and theworm 53 is perpendicular to the rotation axis of the forearm 30. Thethird elastic member 56 may be a torsion spring arranged around thepivot shaft 57 between the hand 40 and the worm 53. Two arms of thetorsion spring are respectively connected to the hand 40 and the worm53.

In one embodiment, the arm assembly 1000 further includes a hand shield41 rotatably connected to the forearm 30 and a fifth elastic member 43that is connected to the forearm 30 and used to apply a restoring forceto the hand shield 41 when the hand 40 rotates from the extension stateto the original state. The hand shield 41 protects the hand 40 andprevents external forces from damaging joint of the hand 40. The handshield 41 is rotatably connected to the forearm shield 32 via a pivotshaft 42. The free end of the hand shield 41 abuts against the dorsum ofthe hand 40. The fifth elastic member 43 may be a torsion springarranged around the pivot shaft 42 between the hand shield 41 and theforearm shield 32. Two arms of the torsion spring are respectivelyconnected to the hand shield 41 and the forearm shield 32. When the hand40 extends with respect to the forearm 30, the hand shield 41 will bepushed to rotate and the torsion spring is twisted. When the hand 40rotates back, the torsion spring rebounds and pushes the hand shield 41to return to its original position.

Referring to FIG. 1, a robot according to an embodiment includes an armassembly as described above. The arm assembly uses only one servo todrive the upper arm 20 and the forearm 30, which saves cost andfacilitates simplification of motion control algorithm of the robot.

Although the features and elements of the present disclosure aredescribed as embodiments in particular combinations, each feature orelement can be used alone or in other various combinations within theprinciples of the present disclosure to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed.

What is claimed is:
 1. An arm assembly of a robot comprising a chest,the arm assembly comprising: a servo coupled to the chest; an upper armdriven by the servo; a forearm rotatably coupled to the upper arm; ahand connected to an end of the forearm and rotatable about a first axisextending along a lengthwise direction of the forearm; a handtransmission mechanism connected to the upper arm and the hand; a rotaryjoint, wherein the servo comprises an output shaft, the rotary joint isfixed to the output shaft and the upper arm; and a rotating memberrotatably and coaxially connected to the rotary joint and a fixed postsecurely connected to the chest, wherein the rotating member comprises afirst lever and a second lever that are circumferentially spaced apartfrom each other, the second lever is configured to contact the fixedpost such that the rotating member can be pushed by the fixed post torotate with respect to the rotary joint, when the rotating memberrotates, the first lever is engaged with the hand transmission mechanismto drive the hand transmission mechanism that drives the hand to rotateabout the first axis.
 2. The arm assembly of claim 1, wherein the handtransmission mechanism comprises a first sliding member slidablyconnected to the upper arm and urged to move by the first lever, asecond sliding member slidably connected to the forearm and urged tomove by the first sliding member, and a worm rotatably mounted to theforearm and connected to the hand, the worm comprises a helical tooththat abuts against the second sliding member so as to rotate when pushedby the second sliding member.
 3. The arm assembly of claim 2, whereinthe hand transmission mechanism comprises a first elastic memberconnected to the upper arm and configured to return the first slidingmember to an original position thereof when the first lever isdisengaged from the first sliding member, and a second elastic memberconnected to the forearm and configured to return the worm to anoriginal position thereof.
 4. The arm assembly of claim 2, wherein theupper arm comprises a longitudinal rib extending along a longitudinaldirection thereof and two lateral ribs spaced apart from each other, thefirst sliding member comprises an L-shaped limiting wall, the firstsliding member and the limiting wall form a recess, the longitudinal riband the recess corporately define a sliding direction of the firstsliding member, and the limiting wall and the lateral ribs corporatelydefine a moving range of the first sliding member.
 5. The arm assemblyof claim 1, wherein the forearm comprises a protrusion that isconfigured in such a way that the protrusion applies a push force to thehand when the hand rotates about the first axis and comes into contactwith the protrusion such that the hand rotates with respect to theforearm about a second axis that is perpendicular to the first axis. 6.The arm assembly of claim 5, wherein the hand comprises an elasticmember to apply a restoring force to the hand to rotate the hand aboutthe second axis from an extension state to an original state.
 7. The armassembly of claim 1, further comprising a hand shield rotatablyconnected to the forearm and an elastic member that is connected to theforearm and configured to apply a restoring force to the hand shieldwhen the hand rotates from the extension state to the original state. 8.A robot comprising a chest and an arm assembly, the arm assemblycomprising: a servo coupled to the chest; an upper arm driven by theservo; a forearm rotatably coupled to the upper arm; a hand connected toan end of the forearm and rotatable about a first axis extending along alengthwise direction of the forearm; a hand transmission mechanismconnected to the upper arm and the hand; a rotary joint, wherein theservo comprises an output shaft, the rotary joint is fixed to the outputshaft and the upper arm; and a rotating member rotatably and coaxiallyconnected to the rotary joint and a fixed post securely connected to thechest, wherein the rotating member comprises a first lever and a secondlever that are circumferentially spaced apart from each other, thesecond lever is configured to contact the fixed post such that therotating member can be pushed by the fixed post to rotate with respectto the rotary joint, when the rotating member rotates, the first leveris engaged with the hand transmission mechanism to drive the handtransmission mechanism that drives the hand to rotate about the firstaxis.
 9. The robot of claim 8, wherein the hand transmission mechanismcomprises a first sliding member slidably connected to the upper arm andurged to move by the first lever, a second sliding member slidablyconnected to the forearm and urged to move by the first sliding member,and a worm rotatably mounted to the forearm and connected to the hand,the worm comprises a helical tooth that abuts against the second slidingmember so as to rotate when pushed by the second sliding member.
 10. Therobot of claim 9, wherein the hand transmission mechanism comprises afirst elastic member connected to the upper arm and configured to returnthe first sliding member to an original position thereof when the firstlever is disengaged from the first sliding member, and a second elasticmember connected to the forearm and configured to return the worm to anoriginal position thereof.
 11. The robot of claim 9, wherein the upperarm comprises a longitudinal rib extending along a longitudinaldirection thereof and two lateral ribs spaced apart from each other, thefirst sliding member comprises an L-shaped limiting wall, the firstsliding member and the limiting wall form a recess, the longitudinal riband the recess corporately define a sliding direction of the firstsliding member, and the limiting wall and the lateral ribs corporatelydefine a moving range of the first sliding member.